In typical fashion for you, your conclusion is a...non-sequitur! Your premise, that Toombs advised against attacking based on his own personal prediction, does not necessitate your conclusion that Davis "knew" and invasion "would happen." Rather, it only indicates that in the mind of one of the participants in his government, an invasion was predicted at a time prior to that invasion occurring. Predictions sometimes come true, but they do not necessitate their own actualization. Try again.
According to Toombs that conversation took place when the cabinet issued the orders to take Sumter. By your timeline that decision was made when Davis 'knew' that an invasion 'would happen.'